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Author Billade, Bhushan; Belitsky, Victor; Pavolotsky, Alexey; Lapkin, Igor; Kooi, Jacob
Title ALMA band 5 (163-211 GHz) sideband separation mixer Type Conference Article
Year 2009 Publication Proc. 20th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages 19-23
Keywords SIS mixer, noise temperature, ALMA, band 5
Abstract We present the design of ALMA Band 5 sideband separation SIS mixer and experimental results for the double side band mixer and first measurement results 2SB mixer. In this mixer, the LO injection circuitry is integrated on the mixer substrate using a directional coupler, combining microstrip lines with slot-line branches in the ground plane. The isolated port of the LO coupler is terminated by wideband floating elliptical termination. The mixer employs two SIS junctions with junction area of 3 µm² each, in the twin junction configuration, followed by a quarter wave transformer to match the RF probe. 2SB mixer uses two identical but mirrored chips, whereas each DSB mixer has the same end-piece configuration. The 2S mixer has modular design such that DSB mixers are measured independently and then integrated into 2SB simply by placing around the middle piece. Measurements of the DSB mixer show noise temperature of around 40K over the entire band. 2SB mixer is not fully characterized yet, however, preliminary measurement indicates SSB (un-corrected) noise temperature of 80K.
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Call Number Serial 616
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Author Li, Chao-Te; Chen, Tse-Jun; Ni, Tong-Liang; Lu, Wei-Chun; Chiu, Chuang-Ping; Chen, Chong-Wen; Chang, Yung-Chin; Wang, Ming-Jye Shi, Sheng-Cai
Title Development of SIS mixers for SMA 400-520 GHz band Type Conference Article
Year 2009 Publication Proc. 20th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages 24-30
Keywords SIS mixer, noise temperature, SMA
Abstract SIS junction mixers were developed for SMA 400-520 GHz band. The results show receiver noise temperature around 100 K across the band, with noise contribution from RF loss and IF estimated to be around 50 K and 20K, respectively. Two schemes were used to tune out junction's parasitic capacitance. When a parallel inductor is employed, the input impedance is close to Rn, which facilitates impedance matching between the junction and the waveguide probe. Waveguide probes were designed to achieve a low feed-point impedance to match to the junction resistance. Optimum embedding impedances for lower receiver noise temperature were investigated. Performances of two schemes and composition of receiver noise were also discussed.
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Call Number Serial 617
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Author Jackson, B. D.; Hesper, R.; Adema, J.; Barkhof, J.; Baryshev, A. M.; Zijlstra, T.; Zhu, S.; Klapwijk, T. M.
Title Series production of state-of-the-art 602-720 GHz SIS receivers for band 9 of ALMA Type Conference Article
Year 2009 Publication Proc. 20th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages 7-11
Keywords SIS mixer, noise temperature, ALMA, band 9
Abstract The Atacama Large Millimeter/Sub-millimeter Array (ALMA) requires the development and production of 73 state-of-the-art receivers for the 602-720 GHz range – the ALMA Band 9 cartridges. Development and pre-production of the first 8 cartridges was completed between 2003 and 2008, resulting in a cartridge design that meets the project's challenging requirements. The cartridge design remains essentially unchanged for production, while the production and test processes developed during pre-production have been fine-tuned to address the biggest new challenge for this phase – ramping up production to a rate of 2 cartridges per month over 2009-2012.
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Call Number Serial 618
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Author Risacher, C.; Meledin, D.; Belitsky, V.; Bergman, P.
Title First 1.3 THz observations at the APEX telescope Type Conference Article
Year 2009 Publication Proc. 20th Int. Symp. Space Terahertz Technol. Abbreviated Journal
Volume Issue Pages 54-61
Keywords balanced HEB mixer noise temperature APEX telescope stability Allan variance aperture efficiency
Abstract The Atacama Pathfinder EXperiment (APEX) 12m telescope is operating on the Llano Chajnantor, Chile, since 2003 and a set of state of the art sub-millimeter receivers have been installed for frequencies spanning from 150 GHz to 1500 GHz. In 2008, a balanced 1.3 THz Hot Electron Bolometer (HEB) receiver was installed for the atmospheric window 1250-1380 GHz. This instrument is part of a 4-channel receiver cryostat with the other channels being 211-275 GHz, 275-370 GHz and 380-500 GHz Sideband Separating (SSB) SIS receivers. This paper presents the first observations obtained so far with the 1.3 THz band during its first months of operation. The sky measurements were taken during opportunistic commissioning and science verification phases, when the weather conditions were sufficiently good with a Precipitable Water Vapor (PWV) below 0.25 mm, which was the case only a few nights during these months. We present the first observations of the molecular transition CO J=(11-10) line on different sources such as Orion-FIR4, CW-Leo and SgrB2(M). We describe the many challenges and difficulties encountered for achieving successful THz observations from a large sub-millimeter ground-based telescope.
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Call Number Serial 619
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Author Rabanus, D.; Graf, U. U.; Philipp, M.; Ricken, O.; Stutzki, J.; Vowinkel, B.; Wiedner, M. C.; Walther, C.; Fischer, M.; Faist, J.
Title Phase locking of a 1.5 terahertz quantum cascade laser and use as a local oscillator in a heterodyne HEB receiver Type Journal Article
Year 2009 Publication Optics Express Abbreviated Journal
Volume 17 Issue 3 Pages 1159-1168
Keywords QCL heterodyne, 300 uW at 1.5 THz, HEB mixer
Abstract We demonstrate for the first time the closure of an electronic phase lock loop for a continuous–wave quantum cascade laser (QCL) at 1.5 THz. The QCL is operated in a closed cycle cryo cooler. We achieved a frequency stability of better than 100 Hz, limited by the resolution bandwidth of the spectrum analyser. The PLL electronics make use of the intermediate frequency (IF) obtained from a hot electron bolometer (HEB) which is downconverted to a PLL IF of 125 MHz. The coarse selection of the longitudinal mode and the fine tuning is achieved via the bias voltage of the QCL. Within a QCL cavity mode, the free-running QCL shows frequency fluctuations of about 5 MHz, which the PLL circuit is able to control via the Stark–shift of the QCL gain material. Temperature dependent tuning is shown to be nonlinear, and of the order of -16 MHz/K. Additionally we have used the QCL as local oscillator (LO) to pump an HEB and perform, again for the first time at 1.5 THz, a heterodyne experiment, and obtain a receiver noise temperature of 1741 K.
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Call Number Serial 628
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Author Sekine, Norihiko; Hosako, Iwao
Title Intensity modulation of terahertz quantum cascade lasers under external light injection Type Journal Article
Year 2009 Publication Applied Physics Letters Abbreviated Journal Appl. Phys. Lett.
Volume 95 Issue Pages 201106(1-3)
Keywords QCL modulation, THz, terahertz
Abstract We investigated the light-current characteristics of terahertz (THz) quantum cascade lasers under external light injection, which excites interband transitions in the active materials. It was found that the amount of reduction in the THz power was constant for all injection currents above threshold, and the dependence of the reduction amount on the wavelength of the external light was observed to show a resonancelike feature. The dominant intensity modulation mechanism was found to be the loss change caused by interband transitions in the active region. Further, the effective coupling efficiency plays an important role in the intensity modulation.
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Call Number Serial 630
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Author Ryabchun, Sergey; Tong, Cheuk-Yu Edward; Paine, Scott; Lobanov, Yury; Blundell, Raymond; Goltsman, Gregory
Title Temperature resolution of an HEB receiver at 810 GHz Type Journal Article
Year 2009 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal IEEE Trans. Appl. Supercond.
Volume 19 Issue 3 Pages 293-296
Keywords HEB mixer
Abstract We present the results of direct measurements of the temperature resolution of an HEB receiver operating at 810 GHz, in both continuum and spectroscopic modes. In the continuum mode, the input of the receiver was switched between black bodies with different physical temperatures. With a system noise temperature of around 1100 K, the receiver was able to resolve loads which differed in temperature by about 1 K over an integration time of 5 seconds. This resolution is significantly worse than the value of 0.07 K given by the radiometer equation. In the spectroscopic mode, a gas cell filled with carbonyl sulphide (OCS) gas was used and the emission line at 813.3537060 GHz was measured using the receiver in conjunction with a digital spectrometer. From the observed spectra, we determined that the measurement uncertainty of the equivalent emission temperature was 2.8 K for an integration time of 0.25 seconds and a spectral resolution of 12 MHz, compared to a 1.4 K temperature resolution given by the radiometer equation. This relative improvement is due to the fact that at short integration times the contribution from 1/f noise and drift are less dominant. In both modes, the temperature resolution was improved by about 40% with the use of a feedback loop which adjusted the level of an injected microwave radiation to maintain a constant operating current of the HEB mixer. This stabilization scheme has proved to be very effective to keep the temperature resolution of the HEB receiver to close to the theoretical value given by the radiometer equation.
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Call Number Serial 636
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Author Xiaolong Hu; Holzwarth, C.W.; Masciarelli, D.; Dauler, E.A.; Berggren, K.K.
Title Efficiently coupling light to superconducting nanowire single-photon detectors Type Journal Article
Year 2009 Publication IEEE Trans. Appl. Supercond. Abbreviated Journal
Volume 19 Issue 3 Pages 336-340
Keywords optical antennas; SNSPD
Abstract We designed superconducting nanowire single-photon detectors (SNSPDs) integrated with silver optical antennae for free-space coupling and a dielectric waveguide for fiber coupling. According to our finite-element simulation, (1) for the free-space coupling, the absorptance of the NbN nanowire for TM-polarized photons at the wavelength of 1550 nm can be as high as 96% by adding silver optical antennae; (2) for the fiber coupling, the absorptance of the NbN nanowire for TE-like-polarized photons can reach 76% including coupling efficiency at the wavelength of 1550 nm by adding a silicon nitride waveguide and an inverse-taper coupler.
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Call Number RPLAB @ gujma @ Serial 647
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Author Kern, Pierre; Le Coärer, Etienne; Benech, Pierre
Title On-chip spectro-detection for fully integrated coherent beam combiners Type Journal Article
Year 2009 Publication Optics Express Abbreviated Journal Opt.Express
Volume 17 Issue 3 Pages 1976-1987
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Abstract This paper presents how photonics associated with new arising detection technologies is able to provide fully integrated instrument for coherent beam combination applied to astrophysical interferometry. The feasibility and operation of on-chip coherent beam combiners has been already demonstrated using various interferometric combination schemes. More recently we proposed a new detection principle aimed at directly sampling and extracting the spectral information of an input signal together with its flux level measurement. The so-called SWIFTS demonstrated concept that stands for Stationary-Wave Integrated Fourier Transform Spectrometer, provides full spectral and spatial information recorded simultaneously thanks to a motionless detecting device. Due to some newly available detection principles considered for the implementation of the SWIFTS concept, some technologies can even provide photo-counting operation that brought a significant extension of the interferometry domain of investigation in astrophysics. The proposed concept is applicable to most of the interferometric instrumental modes including fringe tracking, fast and sensitive detection, Fourier spectral reconstruction and also to manage a large number of incoming beams. The paper presents three practical implementations, two dealing with pair-wise integrated optics beam combinations and the third one with an all-in-one 8 beam combination. In all cases the principles turned into a pair wise baseline coding after proper data processing.
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Call Number RPLAB @ gujma @ Serial 650
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Author Zhizhon, Yan; Majedi, Hamed A.
Title Optoelectronic mixing in the NbN superconducting nanowire single photon detectors Type Conference Article
Year 2009 Publication Proc. SPIE Abbreviated Journal Proc. SPIE
Volume 3786 Issue Pages 9
Keywords Optoelectronic devices, microwave superconductivity, nonlinearity, single photon detector, superconductivity, nanowire, optical mixing, microwave mixers, amplitude modulation, intensity modulation.
Abstract In this paper, we present our experimental results on the electrically pumped optoelectronic mixing effect exhibited in a niobium nitride (NbN) superconducting nanowire. The experimental setup in order to test the mixer has been reported in detail. This superconductive nanowire optoelectronic mixer demonstrates photodetection and mixing in an integrated manner. We have explored both effects under a great variety of external conditions, such as temperature and bias current, in order to seek potential ways toward quantum optoelectronic detection and mixing by such nanowire device.
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Call Number RPLAB @ gujma @ Serial 651
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